Berlin 2005 – wissenschaftliches Programm

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SYAM: Atomare Präzisionsmassenspektrometrie

SYAM 2: Atomare Pr
äzisionsmassenspektrometrie

SYAM 2.3: Hauptvortrag

Montag, 7. März 2005, 15:00–15:30, HU Senatssaal

Precision mass spectrometry with one and two ions in a Penning trap — •Edmund Myers — Florida State University

In the 1990’s the development of the MIT atomic mass spectrometer produced 13 atomic masses at 10⁻¹⁰ relative precision. These results formed the MIT precision atomic mass table with application to fundamental constants. This mass spectrometer has several special features such as a detector based on a dc-SQUID, and the use of a ’pulse and phase’ technique, analogous to the Ramsey Separated-Oscillatory-Field method, for measuring the cyclotron frequency. In the last few years another new and unique technique has been developed. The two ions to be compared are created in the same trap and positioned in a coupled magnetron orbit. Their cyclotron frequencies are then measured simultaneously. This method suppresses sensitivity to magnetic field fluctuations and uncertainty in the measurement of the axial frequency by two or three orders of magnitude. Successful demonstration of this technique at MIT has led to mass comparison at 7 × 10⁻¹² precision, discovery of rotational-state-dependent polarization-induced cyclotron frequency shifts, and a new test of Einstein’s ’E = mc²’. In 2003 the system was relocated to Florida State University. In Tallahassee additional mass measurements at the 10⁻¹⁰ level using single-ion techniques have been completed. Further development of the sub-10⁻¹¹ two-ion technique, for a high precision atomic mass comparison of tritium/helium-3 relevant to neutrino mass, is in progress.